High-throughput design and characterization of an alumina-containing oxide-forming alloy with enhanced hydrogen uptake resistance

In this work, an alumina-containing oxide-forming alloy was designed using a high-throughput computational screening method with objective of mitigating the hydrogen uptake. The alloy composition was optimized to achieve a wide austenitization window while promoting the formation of alumina-containing oxide layers under atmospheric conditions. Thermodynamic calculations predicted a broad austenitic stability range between 850 °C and 1300 °C and the formation of mixed Fe–Al-based oxides during oxidation in air. Experimental oxidation at 800 °C for 72 h resulted in a continuous mixed oxide layer composed primarily of magnetite, alumina, and spinel. Electrochemical hydrogen charging and thermal desorption spectrometry analysis demonstrated that the oxide layer significantly reduced hydrogen uptake, decreasing the total hydrogen content by more than 50% compared with the condition when oxide is removed. The oxidation treatment also results in BCC_B2–NiAl formation within the austenite. The hydrogen desorption results revealed four dominant hydrogen trapping sites associated with dislocations, low-angle grain boundaries, high-angle grain boundaries within the BCC_B2–NiAl and the BCC_B2–NiAl/austenite interface. The latter exhibited a high activation energy (∼73 kJ/mol), indicating strong and irreversible hydrogen trapping, with hydrogen retained even after 24 h of air exposure following electrochemical charging. This work highlights the role of oxide-layers in mitigating hydrogen uptake and elucidates the BCC_B2–NiAl/austenite interface as a strong, irreversible hydrogen trapping site. Overall, this study demonstrates that CALPHAD-guided alloy design is an effective strategy for developing alloys with enhanced resistance to hydrogen uptake.